[Technical Information] How to detect looseness? Axial repeated load testing.

We will introduce the testing method and test examples of axial repeated load testing in detail using photographs!

In addition to the direction perpendicular to the bolt axis, axial repeated loads can also cause loosening. In the case of axial repeated loads, if the bolt and nut are properly tightened and sufficient initial axial force is applied, even when subjected to a large repeated load of 80% of the bolt yield axial force Fy, it can be understood that even standard hex nuts are less likely to experience rotational loosening. On the other hand, if the initial axial force significantly decreases due to some factor, hex nuts and hex nuts with spring washers will completely experience rotational loosening at 50% of the bolt yield axial force Fy, and even double nuts will see the initial axial force drop to about half. From the above results, it can be understood that in the case of hard lock nuts, even when the initial axial force is low or decreases due to some factor, they are less likely to experience rotational loosening. *For more details, please refer to the PDF document or feel free to contact us.

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